1. Field of the Invention
The present invention relates to a method for manufacturing an ink jet recording head that records by discharging recording liquid onto a recording sheet. The invention also relates to an ink jet recording head manufacturing by such method of manufacture, and an ink jet recording apparatus having such ink jet recording head mounted thereon. More particularly, the invention relates to a method for manufacturing an ink jet recording head, which provides an improved method for coating filling agent on the circumference of the recording elemental substrates that constitute the ink jet recording head. The invention also relates to an ink jet recording head manufactured by such method of manufacture, as well as to an ink jet recording apparatus having such ink jet recording head mounted thereon.
2. Related Background Art
Generally, an ink jet recording apparatus is a recording apparatus that records by discharging recording liquid from the discharge ports onto a recording sheet. The apparatus comprises the ink jet recording head that forms recording liquid droplets which are discharged from the discharge ports, and the supply system that supplies recording liquid to the ink jet recording head.
The aforesaid ink jet recording apparatus is a recording apparatus of the so-called non-impact recording type, which makes it possible to perform a high speed recording on various recording media. The apparatus is also characterized in that it has almost no noises at the time of recording. Therefore, the apparatus is widely adopted as an apparatus that carries the recording mechanism, such as a printer, a word processor, a facsimile equipment, and a copying machine, among some others.
As the typical recording method that adopts the ink jet recording apparatus, there is the one that uses electrothermal converting elements. This method uses electrothermal converting elements for the pressure chamber which is arranged in the vicinity of the discharge ports. With the application of electric pulses that become recording signals provided for such elements to discharge the recording liquid from fine discharge ports as liquid droplets by the utilization of pressure exerted by bubbling (film boiling) of the recording liquid, hence performing the recording on the recording sheet.
Here, for the aforesaid discharge method of recording liquid, there is the type where the recording liquid is discharged in the direction parallel to the substrate having the electrothermal converting elements arranged thereon (that is, an edge shooter). Also, there is the one where the recording liquid is discharged in the direction perpendicular to the substrate where the electrothermal converting elements are arranged thereon (that is a side shooter).
FIG. 1 is a view which shows the general recording elemental substrate. FIG. 2 is a view which shows the state where the recording elemental substrate represented in FIG. 1 is connected with a wiring substrate.
As shown in FIG. 1 and FIG. 2, a plurality of discharge ports 2 are arranged on one side face of the recording elemental substrate 1 with recording elements for discharging recording liquid provided therefor. On the other face, the supply port 3 is arranged open in order to supply the recording liquid to the discharge ports 2 in a length almost equal to the length of the discharge port array 2. Then, the wiring substrate 4 is connected with the recording elemental substrate 1 by the application of the TAB assembling techniques or the like in order to apply the electric pulses for discharging the recording liquid. In this way, the recording element unit 6 is formed. Here, the wiring of the wiring substrate 4 is arranged on the reverse side thereof (not shown).
Also, on the recording elemental substrate 1, the sealing resin A5 is coated to protect the lead lines (not shown) that electrically connect the recording elemental substrate 1 and the wiring substrate 4 from erosion by the recording liquid, as well as from the breakage due to the force that may act from the outside.
FIG. 3 is an exploded perspective view which shows one structural example of the conventional ink jet recording head having the recording element unit 6 illustrated in FIG. 2 is arranged therefor. FIG. 4 is a perspective view which shows the external appearance after the completion of the assembling of the ink jet recording head illustrated in FIG. 3. FIG. 5 is a partially enlarged view of the section taken along line Vxe2x80x94V in FIG. 4.
As shown in FIG. 3 and FIG. 4, a plurality of the recording element units 6a to 6c are adhesively fixed to the upper face of the supporting member 7 through the supporting plates 8a to 8c by the application of the bonding resin A9a to 9c, the bonding resin B10a to 10c, and the bonding resin C11a to 11c. Also, on the side face of the supporting member 7, the wiring integration substrate 12 is fixed in order to put electric signals together for a plurality of wiring substrates 4a to 4c, and then, electrically connected with a plurality of the wiring substrate 4a to 4c. In this respect, a reference numeral 20 designates the ink supply port.
Thus, as shown in FIG. 4, the face of the ink jet recording head on the recording liquid discharge port side is filled with the sealing resin B13 on the supporting plate 8, the opening portion of the recording element unit 6, and the circumference of the wiring substrate 4 (so as not to allow the supporting plate 8 to be exposed), hence protecting the wiring on the reverse side of the wiring substrate 4 from the recording liquid.
Also, in addition to the function that supports and fixes the wiring substrate 4, the supporting plate 8 functions as the heat radiation member that radiates heat generated by the recording elemental substrate 1. For this plate, therefore, it is generally practiced to use aluminum or some other material having good heat radiation. Consequently, as in the case of the wiring substrate 4, the supporting plate 8 should also be protected from the recording liquid by filling the sealing resin B13 on the circumference thereof.
However, the circumference of the recording elemental substrate 1 and the circumference of the wiring substrate 4 of the conventional ink jet recording head are sealed as described above in order to execute the sealing process efficiently in a short period of time (with the sealing resin B13a and 13b in FIG. 5).
As a result, there is a need for securing an area between the recording elemental substrate 1 and the wiring substrate 4 at least in the size which may allow the needle of the sealing resin coating machine to enter between them. The outer dimension of the wiring substrate 4 should then become larger by that portion inevitably.
Also, since the electric wiring pattern on the recording elemental substrate 1 is assembled by the application of the photolithographic techniques in high density up to the circumferential portion of the surface thereof, there is a possibility that even a small chipping on the outer circumference may cause the defective performance. Therefore, in order to protect the exposed portion of the electric wiring of the recording element unit, the filler is filled in the circumference thereof. Then, it is necessary to execute this filling in good precision so that the coating machine is not allowed to touch the recording elemental substrate.
Also, the sealing resin B13 is directly coated on the circumference of the recording elemental substrate 1, which makes it necessary to control the coating amount exactly. If the coating amount is too large, the sealing resin B13 may be caused to spread out to the surface of the recording elemental substrate 1 or the wiring substrate 4. If the recording head is completed in such a state that the sealing resin spreads out, it may become an obstacle when the surface of the recording elemental substrate 1 is cleaned after printing.
Also, depending on the viscosity of the sealing resin B13 and the thixotropy thereof, the cobwebbing phenomenon may take place when the needle of the coating machine leaves the sealing portion. In some cases, the sealing resin B13 adheres to the surface of the recording elemental substrate 1 in stripes, which may also become an obstacle when the cleaning is made as described above.
Also, when both sides of the recording elemental substrate 1 are sealed almost simultaneously, the air should remain to reside inevitably on the reverse side of the connecting portion (that is, the portion where the sealing resin A5 is applied) between the recording elemental substrate 1 and the wiring substrate 4. The bubbles of the air thus residing tend to escape externally by breaking the layer of the sealing resin B13 or to stay on the inner side. If it escapes externally, the layer of the sealing resin B13 is holed to be open, which results in the sealing defects. Further, if the bubbles are broken, the surface of the recording elemental substrate 1 may be stained by the adhesion of the sealing resin B13.
Also, if the bubbles resides on the inner side, the reverse side of the connecting portion (that is, the portion where the sealing resin A5 is applied) between the recording elemental substrate 1 and the wiring substrate 4 becomes hollow. Thus, there is a possibility that the wiring of the wiring substrate 4 is eroded by the recording liquid that may enter the reverse side of the wring substrate 4 from such portion that may become hollow.
Therefore, it is ideal to adopt a coating method which does not allow any bubbles to remain on the reverse side of the connecting portion (that is, the portion where the sealing resin A5 is applied) between the recording elemental substrate 1 and the wiring substrate 4. Then, if the sealing resin B13 is coated directly on the circumference of the recording elemental substrate 1, it is necessary to control the timing, the amount, and the coating frequency when one side of the sealing portion of the recording elemental substrate 1 is coated and the other side thereof is coated as the case may be.
However, if the coating timing, amount, and frequency should be controlled appropriately as described above, there is a fear that the time required for the sealing process is inevitably increased to a considerable extent.
Conventionally, therefore, there is still a room for improvement as to the satisfactory control of the appropriate filling amount in order to execute the filling of the filler in good precision when the filler is filled on the circumference of the recording elemental substrates as has been discussed above.
With a view to solving the problems encountered in the conventional art, the present invention is designed. It is an object of the invention to provide a method for manufacturing an ink jet recording head capable of filling the filler in good precision, while controlling the amount of filler appropriately when the filler is filled on the circumference of the recording elemental substrates, and also, to provide an ink jet recording head thus manufactured, as well as an ink jet recording apparatus having such ink jet recording head mounted thereon.
Also, in order to solve the problems encountered in the conventional art, it is another object of the present invention to improve the structure in which the sealing resin is filled on the circumference of the recording elemental substrates in order to eliminate any electrical and structural defects, and at the same time, to shorten the time required for the manufacturing process, while giving more freedom in designing the recording head, hence providing a method for manufacturing at lower costs an ink jet recording head having higher print quality and reliability, as well as an ink jet recording head thus manufactured, and an ink jet recording apparatus having such ink jet recording head mounted thereon.
In order to achieve the aforesaid objects, a method for manufacturing an ink jet recording head, an ink jet recording head, and an ink jet recording apparatus are structured as follows in accordance with the present invention:
(1) A method for manufacturing an ink jet recording head, which is provided with a recording elemental substrate having discharge port group for discharging ink, an electric wiring substrate electrically connected with the recording elemental substrate, and a supporting member for holding and fixing the recording elemental substrate and the electrical wiring substrate, comprises the following steps of:
injecting thermohardening filler into a filler retaining portion communicated with the sealing area requiring sealing;
filling the area with the thermohardening filler injected into the filler retaining portion by heating the filler to flow; and
hardening the filled thermohardening filler.
(2) An ink jet recording head used for the method for manufacturing an ink jet recording head, which is provided with a recording elemental substrate having discharge port group for discharging ink, an electric wiring substrate electrically connected with the recording elemental substrate, and a supporting member for holding and fixing the recording elemental substrate and the electrical wiring substrate, comprises a filler retaining portion communicated with the sealing area for which sealing is required.
(3) An ink jet recording apparatus, which is provided with a carriage mounting on it the ink jet recording head having a recording elemental substrate provided with discharge port group for discharging ink, an electric wiring substrate electrically connected with the recording elemental substrate, and a supporting member for holding and fixing the recording elemental substrate and the electrical wiring substrate, and which further comprises a filler retaining portion communicated with the area (sealing area) for which sealing is required.
With the structure thus arranged in accordance with the present invention, the sealing resin is not coated directly on the circumference of the recording elemental substrate. As a result, there is no need for securing the space required to allow the needle of the sealing resin coating machine to enter on the circumference of the recording elemental substrates that become the sealing areas, nor between the adjacent recording elemental substrates, hence making it possible to make the outer dimension of the wiring substrates smaller to that extent.
Also, it becomes easier to control the coating amount, because the sealing resin is not coated directly on the circumference of the recording elemental substrate, particularly on the electrode portion, and then, the coating amount rarely changes abruptly.
Also, no cobwebbing phenomenon takes place when the needle of the coating machine leaves the sealing location, because the sealing resin is not coated directly on the circumference of the recording elemental substrate, thus making it possible to prevent the sealing resin from adhering to the surface of the recording elemental substrate.
Also, there is no need for the needle of the coating machine to approach directly the circumference of the recording elemental substrate when the sealing resin is coated. As a result, it becomes possible to eliminate any possibility that chipping occurs on the outer circumference of the recording elemental substrate.
Also, it becomes unnecessary to control the coating timing of the sealing resin between the sealer coating location on one side of the recording elemental substrates and that on the opposite side. As a result, the time required for the coating process can be shortened.
Also, the filler retaining portion is arranged to be communicated with the vicinity of the center of the reverse side where the recording elemental substrate and the wiring substrate are electrically connected. Thus, the sealing resin is filled beginning with such portion to avoid the presence of residual bubbles.
Also, with the supporting substrate being inclusively arranged between the recording elemental substrate and the supporting member, it becomes possible to fill the filler through a plurality of communication holes by only one coating with the provision of the plurality of the holes which are communicated from the filler retaining portion to the sealing area. In this manner, the time required for the filling process can be shortened.
As described above, in accordance with the present invention, it is possible to provide a highly reliable high print quality ink jet recording head at lower costs without electrical and structural defects.